b-tree

问题 How many nodes does a resulting B-Tree(min degree 2) have if I insert numbers from 1 to n in order? I tried inserting nodes from 1 to 20 there was a series for the number of nodes coming but i could not generalize it. Can anyone please help me derive the formula for this. 回答1: It will depend on the order of the B-Tree. The order of a BTree is the maximum number of children nodes a non-leaf node may hold (which is one more than the minimum number of keys such a node could hold). According to

问题 I am trying to find out which will be more efficient in terms of speed of search, whether trie or B-Tree. I have a dictionary of English words and I want to locate a word in that dictionary efficiently. 回答1: If by "more efficient in time of search" you refer to theoretical time complexity, then B Tree offers O(logn * |S|) 1 time complexity for search, while a trie offers O(|S|) time complexity, where |S| is the length of the searched string, and n is the number of elements in dictionary. If

问题 I got this simple question Calculate the order p of a B+ tree if B=512, V=9B, Pr=7B and P=6B. I think the answer is 6p + (p - 1) * 9 < 512 which ignore the Pr but if change the question is to calculate order p of a B-Tree with same values for B,Pr, P and B then, I think the answer should be 6p + (p - 1) * (9 + 78) < 512 Am I correct on this? 回答1: Each B Tree node can have at most p tree pointers, and p-1 data pointers and p-1 search key fields values. These must fit into a single disk block

问题 I am trying to implement a B+ tree myself, but I want to create a method that prints what elements does the B+ tree have. If I use a traversal(in or post order) I will get also the elements in the parent nodes, therefore I will have duplicate values. Is there a way to solve this thing? Thanks 回答1: Mark the nodes as you traverse them. Once the node is marked, it can't be traversed. 来源： https://stackoverflow.com/questions/9917715/b-tree-print-elements-is-order

问题 I would like to know a few things regarding mysql architecture. 1. How sql process insert, delete, update operations in an indexed table? 2. It is said that changes are only made in the change buffer when the index page is not in the buffer pool. So if changes are made after the buffer pool loads the concerned index page, then it has to alter the same page in disk as well. right? So an operation has to be done in three different places? 3. How NULL values are indexed? where would they be

问题 I have been thinking about two questions. Couldn't find any resources on the internet about this. How do dbms handle it ? Or do they ? Especially Oracle. Before the questions, here is an example: Say I have a master table "MASTER" and slave table "SLAVE". Master table has an "ID" column which is the primary key and index is created by Oracle.Slave table has the foreign key "MASTER_ID" which refers to master table and "SLAVE_NO". These two together is the primary key of slave table, which is

问题 Has anyone seen an implementation of the STL where stl::set is not implemented as a red-black tree? The reason I ask is that, in my experiments, B-2B trees outperform stl::set (and other red-black tree implementations) by a factor of 2 to 4 depending on the value of B. I'm curious if there is a compelling reason to use red-black trees when there appear to be faster data structures available. 回答1: Some folks over at Google actually built a B-tree based implementation of the C++ standard

问题 I am trying to understand what should drive the choice of the access method while using a BerkeleyDB : B-Tree versus HashTable. A Hashtable provides O(1) lookup but inserts are expensive (using Linear/Extensible hashing we get amortized O(1) for insert). But B-Trees provide log N (base B) lookup and insert times. A B-Tree can also support range queries and allow access in sorted order. Apart from these considerations what else should be factored in? If I don't need to support range queries

问题 Is it 2n? Just checking. 回答1: Terminology The Order of a B-Tree is inconstantly defined in the literature. (see for example the terminology section of Wikipedia's article on B-Trees) Some authors consider it to be the minimum number of keys a non-leaf node may hold, while others consider it to be the maximum number of children nodes a non-leaf node may hold (which is one more than the maximum number of keys such a node could hold). Yet many others skirt around the ambiguity by assuming a

问题 Is there any file system based B+ Tree implementation in c#(open source). I have found some projects, but those are not file(disk) based implementation. I am specifically looking for file system based B+ Trees. 回答1: Update: I've added some benchmarks of managed B-Tree implementations for your enjoyment if you looking into this sort of thing. BplusDotNet "... is known to be somewhat buggy on deletes" I found just the opposite to be true, RaptorDB 1.6 was corrupting state and BplusDotNet 1.0